In cellular systems, such as networks operating under the Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE) standard initiated by the third-generation partnership project (3GPP) or the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (WiMax), transmissions may travel via an infrastructure path through a core network. When wireless mobile devices (e.g., user equipments or “UEs”) are in proximity to one another, the infrastructure path represents a waste of network channel and user battery resources. To avoid this waste and improve UE and network performance, direct communications protocols are being investigated in 3GPP systems for the purpose of offloading data traffic onto direct links between UEs.
While efforts are being made in 3GPP systems to develop a new LTE-based device-to-device (D2D) protocol, there are many D2D protocols that exist in distributed networks, which can be used to offload network traffic onto direct links. Because such D2D protocols are designed for distributed networks, however, they do not have a central management. Thus, the D2D protocols use contention-based procedures to manage radio resources. Since the contention-based D2D protocols are non-cellular protocols, they reside on bands other than the cellular network and are useful for the purpose of offloading cellular network traffic. Unfortunately, the contention-based D2D protocols do not always perform well with respect to user throughput, delay, and/or battery power.